Them: You keep replacing pickups, this will devalue your guitar.
Me: Definitely not. A pickup's worthiness depends on the user. If it doesn't serve the user's needs, it's better off replaced. Some people put high hopes on pickups in certain guitars in view of the brand name; Gibson, Fender & Suhr, among others. Nothing wrong with that but it prevents a true evaluation of the pickups' worthiness. If they don't work for you, then they don't work for you, regardless of the brand name.
Them: You're saying the replacements are always better?
Me: Definitely not as well. There is a good chance the replacements are what the player prefer if they dislike the default ones to begin with. This is especially true if the player has a history of using the pickup brand in other guitars. They know what works for them.
Them: In that case, why don't guitar manufacturers just put good, branded pickups in their instruments to begin with?
Me: They do. The Jackson DKR you see above, for instance, feature a pair of DiMarzio pickups (Super Distortion / PAF Pro). There are other examples of course. They are not doing so for all guitars, it depends on the tier the instruments are in. The beginner / starter models often feature in-house pickups to keep prices down.
Them: What are examples of good pickup brands?
Me: There are none. What is good for you might not be the case for me. There is a higher chance of you liking a certain brand name as opposed to something that is so good, it outperforms all others. If that's the case, there should only be one pickup brand, yes? Because the rest are awful; you follow?
Pic: Jackson